so like 100 square feet?

Though the rooftop solar isn't optimal from an efficacy standpoint, it has other selling points. You have residential solar and a battery? Congratulations, you don't have to worry so much about power outages. This is particularly a selling point for rural living, where outages happen more often and last longer.

The abstract "it's greener" is a less potent sales pitch than "your fridge, heating, and a/c can still work even if the grid is gone".

For energy generation, being close to the point of usage prevents waste from energy transport. For energy storage it's probably more efficient to do this at larger scale, which means centralized systems.

So I think it's more complicated and depends on a lot of factors. Stating "Centralization is more efficient and less wasteful" as a hard fact is misleading at best.

Having centralized solar doesn’t preclude a homeowner from also installing solar, and decentralized green energy has other advantages over centralized green energy.

less wasteful

Where’s the waste? If you collect more than you use, you can store it or send it back to the grid. If this is an efficiency concern (“you’re collecting less energy than the same amount of paneling would”), then it’s not really relevant as by that same logic, not having solar is “more wasteful” than having it.

It could just be the same thing. Total houses in community. Apply solar cells to already owned government land or near where the current plant is anyway like most already have been doing. Just scale up and add wind in. Salt batteries all over. Bam.

The beauty of solar is it scales up/down without much fuss whereas you can’t just run a coal fire plant for your home. We can build what makes sense for each community/home.